The trophozoites of Entamoeba histolytica, the cause of human amebiasis adhere to colonic mucins, intestinal epithelium and leukocytes via a galactose-specific lectin. The lectin is a major conserved surface antigen which is recognized by the immune sera of 99 percent of tested patients with amebic liver abscess and colitis. Inhibition of this lectin with galactose prevents adherence and contact- dependent killing of immune effector cells such as neutrophils and macrophages. The lectin also mediates amebic resistance to the human complement membrane attack complex. Preliminary evidence indicate that the recombinant-expressed lectin is a more specific serodiagnostic reagent for acute amebiasis. In addition, the recombinant lectin is a protective antigen in an animal model of amebiasis. Dr. Lyerly proposes the development a more specific EIA for serodiagnosis of amebiasis using recombinant expressed amebic adherence lectin. Experience acquired in expression of fragments of the lectin gene for the EIA will be applied towards future development of a vaccine against amebiasis..